Lack of clarity in Twitter’s privacy policy reminds social media users that their personal data is not theirs alone

Twitter is the latest social network to disclose that it handles users’ personal information in ways that are not made entirely clear to them when they sign up for the service.

As Twitter revealed this week, it has been copying its users’ address books and storing the information on its servers for as long as 18 months. Twitter’s privacy policy does tell users they can customize their account, including their address books, to make it easier, through Twitter’s Find Friends option, to locate users they may know, a recent Los Angeles Times story points out. But it doesn’t explicitly say that the service downloads all address-book entries and stores them.

Google (NASDAQ:GOOG), too, has been dogged by user concerns over its recently announced plan to apply a single privacy policy to nearly all of its services, without providing an opt-out option, and on Friday Google faced additional criticism over the revelation that it and a few online ad companies had dodged privacy controls set by iPhone users.

Privacy policy and a world of uncertainty

Obviously, user expectations and attempts at clarity from companies come into play in a major ways when online services develop their privacy guidelines, and expectations and clarity (or lack of it) play a huge role in the public response to privacy failures.

When most social network users log into social networking services such as Facebook, LinkedIn (NYSE:LNKD), or Google Plus, it’s usually to share information with a select group that might include family, friends, or colleagues.

And when Twitter users send out their mini-messages, they often are sharing some bit of news with their Twitter followers and, eventually, much of the broader Twitter community. In fact, Twitter has emerged as an influential, if not official, news source. One example: Twitter users broke the news of Whitney Houston’s death in Los Angeles before mainstream media sources began their coverage.

So Twitter users, many of whom are not trained journalists, should be concerned when the mini-blogging service admits it has copied and stored their personal contact information without their permission.

When traditional media tries subterfuge

Mainstream news organizations can’t sneak unauthorized peaks into private citizens’ personal lives without risking significant and expensive backlash. Just ask News Corp.’s (NYSE:NWS) former News of the World staffers. News Corp. chief executive Rupert Murdoch shut down the London-based tabloid newspaper amid reports that staffers and investigators hired by the paper hacked into cell phone voice mails of scores of people, including of a missing 13-year girl who was later found dead. The cell phone hacking in that case compromised a police investigation, and led investigators and the girl’s family to believe she might be alive.

Accusations of hacking also afflict another Murdoch paper in Britain, The Sun. Murdoch this week arrived in London to offer his “unwavering support” to the paper, although he added that he won’t protect reporters who have broken the law.

Twitter’s failure to make its data collection practices clear to users is obviously in an entirely different realm and certainly not tied to criminal activity. But to many people it is still disquieting. Twitter, and other players in the social media sector, are under increasing pressure to gather data and monetize it, but also to do it in a way that doesn’t generate mistrust, drive away users, and, perhaps, investors.

“In our next app updates, which are coming soon, we are updating the language associated with Find Friends – to be more explicit,” Twitter spokeswoman Carolyn Penner wrote in an email to the Los Angeles Times. “In place of ‘Scan your contacts,’ we will use ‘Upload your contacts.’”